Question

What is the derivative of `f(x)=cos(pi/2-x)`?

Answer 1

`d/dx cos (pi/2-x) = cosx`

Explanation:

Using the trigonometric formula:

`cos(alpha-beta) = cos alpha cos beta + sin alpha sin beta`

we have:

`cos (pi/2-x) = sinx`

so:

`d/dx cos (pi/2-x) = d/dx sinx = cosx`